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pygame写贪吃蛇

2018-06-18 01:27:53来源：未知阅读 ()

python小白尝试写游戏..

学了点pygame不知道那什么练手好,先拿贪吃蛇开刀吧.

一个游戏可以粗略的分为两个部分:

数据(变量)
处理数据(函数,方法)

设计变量

首先预想下,画面的那些部分需要存储在变量里

整个画面上只会有矩形,而且这些矩形整整齐齐,大小相等,原本一个矩形需要四个变量表示位置,这里,只需要两个变量(行数,列数)就能表示方块的位置

蛇头,食物可以用二元元组表示,蛇身的数量不确定,只能用包含数个元组的列表表示

另外设定窗口大小800x600,每个方块都是50x50

import pygame
import sys

pygame.init()
screen = pygame.display.set_mode((800, 600))
pygame.display.set_caption("贪吃蛇")

food = (4, 5)
body = [(1, 1),(1,2)]
head = (1, 3)

BLOCK = 0, 0, 0
GREEN = 0, 255, 0
RED = 255, 0, 0
BLUE = 0, 0, 255
WHITE = 255, 255, 255

while 1:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()

变量设定好了,游戏已经完成了一半(￣▽￣)~*

下一步

变量到画面

pygame.draw.rect()是根据矩形四元数组绘制图像的,那就写个函数"对接"下我的二元坐标

这里就成数学的问题了...

def new_draw_rect(zb, color,screen):
    pygame.draw.rect(screen,color,((zb[1]-1)*50+1,(zb[0]-1)*50+1,48,48))

鉴于50x50时相邻方块们会"粘"在一起,方块向里收一下成48x48 ↑

绘制图形,

...
while 1:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()

    screen.fill(WHITE)
    new_draw_rect(food, RED, screen)
    for i in body:
        new_draw_rect(i, BLUE, screen)
    new_draw_rect(head, GREEN, screen)
    
    pygame.display.update()

由静到动

两个问题:

1.什么时候动

2.怎么动

问题1,什么时候动,这里有两个思路,

间隔固定时间(1秒),动一次
按一次键动一次,无操作一定时间(1秒)后,重复最后一次操作

看起来第一种方案简单不错

首先,先用pygame的clock类限制帧率(100帧),以方便计时

再者,加入新变量times,times每次加1,超过一百就"动一动"

加入新变量direction,表示蛇头朝向,衔接键盘操作和"怎么动"

PS:程序结束之前,很难知道要用多少变量

import pygame
import sys

pygame.init()
screen = pygame.display.set_mode((800, 600))
pygame.display.set_caption("贪吃蛇")

fclock = pygame.time.Clock()


food = (4, 5)
body = [(1, 1)]
head = (1, 2)
times = 0
direction = 'right'

BLOCK = 0, 0, 0
GREEN = 0, 255, 0
RED = 255, 0, 0
BLUE = 0, 0, 255
WHITE = 255, 255, 255

def new_draw_rect(zb, color,screen):
    pygame.draw.rect(screen,color,((zb[1]-1)*50+1,(zb[0]-1)*50+1,48,48))
    pass


while 1:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP:
                direction = "up"
            elif event.key == pygame.K_LEFT:
                direction = "left"
            elif event.key == pygame.K_DOWN:
                direction = "down"
            elif event.key == pygame.K_RIGHT:
                direction = "right"
    if times >= 100:
        pass#动一动
        times = 0
    else:
        times += 1

    screen.fill(WHITE)
    new_draw_rect(food, RED, screen)
    for i in body:
        new_draw_rect(i, BLUE, screen)
    new_draw_rect(head, GREEN, screen)

    fclock.tick(100)
    pygame.display.update()

蛇头的运动规律 : 向临近的格子移动,上下左右具体那个格子由键盘确定

那就写个新函数去生成蛇头的新位置

def get_front(head,direction):
    x, y = head
    if direction == "up":
        return x-1, y
    elif direction == "left":
        return x, y-1
    elif direction == "down":
        return x+1, y
    elif direction == "right":
        return x, y+1

然后

head = get_front(head,direction)

但是蛇蛇一头扎墙里怎么办.......

你的好友【front : 临时记下蛇头前方的位置】已上线

你的好友【alive : 记录存活信息】已上线

PS:front可以不是全局变量

def ask_alive(front,body):
    x, y = front
    if x < 0 or x > 12 or y < 0 or y >16 :
        return False
    if front in body:
        return False
    return True

然后这样用

front = get_front(head,direction)
alive = ask_alive(front,body)
if alive:
　　head = front

人话 :先看看蛇头前面是否有危险,有危险就死了 , 不动啦

另外alive得加到前面的if里面当限制条件,死了就不能乱动啦~~~~~

蛇身动的规律 : 近头端跟头走,尾端也跟着走--向程序靠拢-->>用过的head加入body,同时删去body最老的成员

这里可以看出body必须有序,可变.python里面就用列表了

如果使用list的append方法,head加在body的末尾,那么body[0]就会是"最老的成员"就得使用pop(0)删去

PS. body.append(head)得写在head=front前面,在head更新前加进body

    if times >= 100 and alive:
        front = get_front(head,direction)
        alive = ask_alive(front,body)
        if alive:
            body.append(head)
            head = front
            body.pop(0)
        times = 0
    else:
        times += 1

食物的运动规律:被吃掉后,随机位置再出现 --向程序靠拢-->> 当head== food为真时 food随机选择一个蛇之外的地方出现

def new_food(head,body):
    while 1:
        x = random.randint(1, 12)
        y = random.randint(1, 16)
        if (x, y) != head and (x, y) not in body:
            return x, y

这里存在一个隐式BUG,要是蛇充满了每一个角落,那这就是死循环 ...........然后整个程序卡在这里....

版本1 : 我选择没看见,不会有什么人能吃到"全屏"的(′⊙ω⊙`) --来自开发者的懒惰

版本2 【我的选择】: 修了这个BUG

def new_food(head,body):
    i = 0
    while i < 100:
        x = random.randint(1, 12)
        y = random.randint(1, 16)
        if (x, y) != head and (x, y) not in body:
            return (x, y), True
        i += 1
    else:
        return (0, 0), False

food, alive = new_food()

100次机会否则就死(￣へ￣) --来自开发者的恶意

另外,蛇吃了食物就要长一格====>>蛇头前进一格,蛇尾不动,蛇就因此长了一格====>>当head = food 为真时body.pop(0)不用执行

        if alive:
            body.append(head)
            head = front
            if food == head:
                food = new_food(head, body)
            else:
                body.pop(0)

完结撒花

细节优化

什么?游戏结束了?

黑个屏,提醒下

你的好友【back_color】已上线

back_color一开始等于WHITE , alive为假时变为BLOCK

标题栏变成"游戏结束"

    if times >= 100 and alive:
        front = get_front(head, direction)
        alive = ask_alive(front, body)
        if alive:
            body.append(head)
            head = front
            if food == head:
                food, alive = new_food(head, body)
            else:
                body.pop(0)
        else:
            back_color = BLOCK
            pygame.display.set_caption("游戏结束")
        times = 0
    else:
        times += 1

要是一开始按了一下left......

恭喜你获得技能【撞脖子自杀】

要么那就

你的好友【old_direction】已上线

old_direction = "right"

def direction_yes_no(direction,old_direction):
    d = {"up": "down", "down": "up", "left": "right", "right": "left"}
    if d[direction] == old_direction:
        return old_direction
    return direction

PS : 字典代替if-elif结构省心省时

然后

　　if times >= 100 and alive:
        direction = direction_yes_no(direction, old_direction)
        old_direction = direction
        front = get_front(head, direction)
        alive = ask_alive(front, body)

人话 : 添加一个变量记录上一次有效的输入,两个方向关系不正确时,以老变量为准--向人靠拢-->>向右跑时,不准向左!!!

Q : direction也可以在按键事件处理时限制呀,例如

        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP:
                direction = "up"
                   """改为"""
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP:
                if direction != "down"
                    direction = "up"

A:在发现这个方法的BUG之前,我也是这样想的

还是上面的例子

直接按left行不通,right--XX-->left

先按down,迅速再按left ,,right --pass-->> down --pass-->> left

恭喜你获得技能【绕过开发者防护,高水平撞脖子自杀】

Q : 我要暂停!!!

A : 好好玩游戏,不要动不动就暂停

你的好友【pause】已上线

逻辑值,P键控制

pause = False

            elif event.key == pygame.K_p:
                pause = not pause    

if times >= 100 and alive and (not pause):
    ....

下面我发一下全部的代码,代码包含上面的优化

↓↓↓↓

完结撒花

import pygame
import sys
import random

pygame.init()
screen = pygame.display.set_mode((800, 600))
pygame.display.set_caption("贪吃蛇")

fclock = pygame.time.Clock()


food = (4, 5)
body = [(1, 1)]
head = (1, 2)

times = 0
direction = "right"
old_direction = "right"
alive = True
pause = False

BLOCK = 0, 0, 0
GREEN = 0, 255, 0
RED = 255, 0, 0
BLUE = 0, 0, 255
WHITE = 255, 255, 255
back_color = WHITE


def new_draw_rect(zb, color,screen):
    pygame.draw.rect(screen,color,((zb[1]-1)*50+1,(zb[0]-1)*50+1,48,48))


def get_front(head, direction):
    x, y = head
    if direction == "up":
        return x-1, y
    elif direction == "left":
        return x, y-1
    elif direction == "down":
        return x+1, y
    elif direction == "right":
        return x, y+1


def ask_alive(front, body):
    x, y = front
    if x < 0 or x > 12 or y < 0 or y >16 :
        return False
    if front in body:
        return False
    return True


def new_food(head, body):
    i = 0
    while i < 100:
        x = random.randint(1, 12)
        y = random.randint(1, 16)
        if (x, y) != head and (x, y) not in body:
            return (x, y), True
        i += 1
    else:
        return (0, 0), False


def direction_yes_no(direction, old_direction):
    d = {"up": "down", "down": "up", "left": "right", "right": "left"}
    if d[direction] == old_direction:
        return old_direction
    return direction

#food = new_food(head,body)

while 1:
    for event in pygame.event.get():
        if event.type == pygame.QUIT:
            sys.exit()
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP:
                direction = "up"
            elif event.key == pygame.K_LEFT:
                direction = "left"
            elif event.key == pygame.K_DOWN:
                direction = "down"
            elif event.key == pygame.K_RIGHT:
                direction = "right"
            elif event.key == pygame.K_p:
                pause = not pause
    if times >= 100 and alive and (not pause):
        direction = direction_yes_no(direction, old_direction)
        old_direction = direction
        front = get_front(head, direction)
        alive = ask_alive(front, body)
        if alive:
            body.append(head)
            head = front
            if food == head:
                food, alive = new_food(head, body)
            else:
                body.pop(0)
        else:
            back_color = BLOCK
            pygame.display.set_caption("游戏结束")
        times = 0
    else:
        times += 1

    screen.fill(back_color)
    new_draw_rect(food, RED, screen)
    for i in body:
        new_draw_rect(i, BLUE, screen)
    new_draw_rect(head, GREEN, screen)

    fclock.tick(100)
    pygame.display.update()

↑↑↑↑

Q : 游戏结束或者暂停后因为times >= 100 and alive and (not pause)始终为假

times += 1 一直运行,,,,会不会不太妥当

A : 又不会溢出,,,,,,,,取消暂停时蛇能迅速跑起来要是time==100那问题就大了,,幸亏当初留了些余地写成 >=

(～￣▽￣)～

Q : 蛇跑的太慢我想加速

A : 上面的times>=100的100随便改一下就行

0->100动一动变成 0->80 动一动

或者动前面的数

0->100动一动变成 20->100动一动

或者将它设置成变量让它随蛇的长度变化而变化

打字太累,,

direction那里可以使用0,1,2,3

代替 up left down right

键盘事件和get_front()得用同一套词

Q : 第一个food的位置是固定的,不能"动"吗?

A : 因为我是先定义变量,再定义函数

food = new_food(head,body)

就得写在定义函数后面,我不忍心让它一个变量孤单,,,,怕你看不到(写了但注释掉了)

动手术

前面说过

问题1,什么时候动,这里有两个思路,

间隔固定时间(1秒),动一次

按一次键动一次,无操作一定时间(1秒)后,重复最后一次操作

看起来第一种方案简单不错

当初我以为第二种方案很难,,,

写了这个博客后实力大增?( ? ? ? )?

现在我不怕了

第一个方法,

处理按键事件后times = 100 ,例

    if event.key == pygame.K_UP:
        direction = "up"
        times = 100
    elif event.key == pygame.K_LEFT:
        direction = "left"
        times = 100

while循环当轮就能动一动

隐藏操作 : 在0.01s内按下两个键,第一个按的不会"生效"

pygame : 我得跑完事件列表的每个元素

这是假的第二方案!!!

第二个方法,

把"动一动"的全部代码,打包成函数或者直接写在按键处理的后面

就是上面times = 100的位置例

    if event.key == pygame.K_UP:
        direction = "up"
        '动一动'
    elif event.key == pygame.K_LEFT:
        direction = "left"
        '动一动'

记住关键的一点times = 0也算"动一动"的内容,第二方案里,按键后计时需要清零!!!

    if times >= 100 and alive and (not pause):
        direction = direction_yes_no(direction, old_direction)
        old_direction = direction
        front = get_front(head, direction)
        alive = ask_alive(front, body)
        if alive:
            body.append(head)
            head = front
            if food == head:
                food, alive = new_food(head, body)
            else:
                body.pop(0)
        else:
            back_color = BLOCK
            pygame.display.set_caption("游戏结束")
        times = 0
    else:
        times += 1

为了防止"诈尸"

"动一动"前还得加上if alive and (not pause):

times没必要加

我就懒得管了(╥╯^╰╥)这篇文章写了太长时间,现在已经看不懂当初的代码了

Q : 不知道你是不是记得我,优化2就是我问的.....是这样的,我对我的方法还不死心...."动手术"改第二方案后能用吗?

        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP:
                direction = "up"
                   """改为"""
        elif event.type == pygame.KEYDOWN:
            if event.key == pygame.K_UP:
                if direction != "down"
                    direction = "up"